title: Increasing occurrence of antimicrobial-resistant hypervirulent (hypermucoviscous) Klebsiella pneumoniae isolates in China.
abstract: BACKGROUND
  New hypervirulent variants of Klebsiella pneumoniae (hvKP) are emerging globally, most of which exhibit antimicrobial susceptibility.
  
  
  METHODS
  A retrospective study was conducted in 88 patients with cultures positive for K. pneumoniae hospitalized in the Beijing You'an Hospital from April 2010 to June 2012. The clinical and molecular data of the hvKP isolates (defined as string test positive) were compared with those of the classic K. pneumoniae (cKP) isolates.
  
  
  RESULTS
  Overall, 33.0% (29/88) of K. pneumoniae isolates were hvKP. Univariate analysis revealed the following risk factors for hvKP: virulence gene rmpA (odds ratio [OR], 16.92 [95% confidence interval {CI}, 4.842-59.145]), capsule antigens K1 (OR, 3.355 [95% CI, 1.153-9.768]) and K2 (OR, 9.280 [95% CI, 0.987-87.250]), alcoholic hepatitis (OR, 7.435 [95% CI, 1.397-39.572]), liver abscess (OR, 9.068 [95% CI, 1.747-47.061]), metastatic infection (OR, 2.752 [95% CI, 1.100-6.886]), community-acquired infection (OR, 10.432 [95% CI, 3.623-30.033]), sputum isolation (OR, 0.312 [95% CI, .095-1.021]), and HIV infection (<0.001 [not applicable]). Multivariate analysis implicated rmpA (OR, 17.398 [95% CI, 4.224-71.668]) and community-acquired infection (OR, 6.844 [95% CI, 1.905-24.585]) as independent risk factors. The proportion of hvKP isolates increased from April to December 2010, January to September 2011, and October 2011 to June 2012 (to 25.5%, 26.7%, and 54.5%, respectively). Resistance to 14 of 19 tested antimicrobials was found to be significantly greater in cKP compared to hvKP. Importantly, resistance to all the tested antimicrobials, except carbapenems and amikacin, was observed in a proportion of hvKP strains, 17% (5/29) of which expressed extended-spectrum β-lactamase. Furthermore, antimicrobial resistance in hvKP strains increased over time.
  
  
  CONCLUSIONS
  HvKP strains are being isolated from patients in China with increasing frequency and constitute an increasing proportion of K. pneumoniae strains, indicating an increasing propensity for the acquisition of antimicrobial resistance.
authors.affiliation: Department of Infectious Diseases.
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.forename: Guizhen
authors.initials: G
authors.lastname: Sun
authors.forename: Yanhua
authors.initials: Y
authors.lastname: Yu
authors.forename: Ning
authors.initials: N
authors.lastname: Li
authors.forename: Ming
authors.initials: M
authors.lastname: Chen
authors.forename: Ronghua
authors.initials: R
authors.lastname: Jin
authors.forename: Yanmei
authors.initials: Y
authors.lastname: Jiao
authors.forename: Hao
authors.initials: H
authors.lastname: Wu
mesh_terms: D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002681:China / Q000453:epidemiology; D021821:Communicable Diseases, Emerging / Q000453:epidemiology* / Q000382:microbiology; D024881:Drug Resistance, Bacterial; D005260:Female; D006801:Humans; D015994:Incidence; D007710:Klebsiella Infections / Q000453:epidemiology* / Q000382:microbiology; D007711:Klebsiella pneumoniae / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012189:Retrospective Studies; D014774:Virulence; D037521:Virulence Factors / Q000032:analysis* / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D037521:Virulence Factors
keywords: Klebsiella pneumoniae; antimicrobial resistance; clinical features; epidemiology; hypervirulent